The field of the disclosure relates generally to fiber communication networks, and more particularly, to access networks capable of transmitting coherent optical signals.
Fiber-to-the-premise (FTTP) based access networks have been widely deployed in many regions of the world. Increasing demand for high-speed data and video services is presently driving growth in access bandwidth requirements, up to gigabits per second (Gb/s) for residential offerings and multi-Gb/s for business. Conventional FTTP network architectures utilize a passive optical network (PON), for example, a Gigabit passive optical network (GPON) within ITU-T, or an Ethernet passive optical network (EPON) within IEEE. PON can be point-to-multipoint, and is often an economical alternative to point-to-point Ethernet for moderate to large populations. Recent GPON and EPON networks realize 2.5/1.25 Gb/s data rates for downstream and 1.25 Gb/s upstream, respectively, and more recently includes 10-Gb/s PON (XG-PON or IEEE 10G-EPON) for high-bandwidth applications. GPON and EPON have some technical differences in terms of signal encapsulation and dynamic bandwidth allocation, but both PON types are capable of carrying data over fiber through a passive optical network all the way from an optical hub to a customer premise. Both PON types use baseband digital signaling over the fiber to carry information.
Cable operators now regularly offer Gb/s service to residential offerings, and access bandwidth requirements therefrom are expected to grow to multi-Gb/s speeds in response to increasing 4K/8K video streaming, proliferation of cloud computing, “big data,” social media, Internet of Things (IoT), and mobile data delivery. Conventional wired networks that are based on PON access technologies have become a dominant architecture to meet such high-capacity demand for end users. Increasingly, PONs are expected to evolve to provide higher per-subscriber data rates and wider coverage of services and applications, while at the same time minimizing capital expenditure (CAPEX) and operating expenditure (OPEX) costs, and also increasing reconfigurable capability for scalable solutions.
However, conventional PON architectures that use direct detection schemes are unable to address these technological support requirement challenges because of the low receiver sensitivity and limited upgrading options in such architectures. Conventional PON architectures are limited in their distance reach, and also in the split ratio they are able to maintain. Conventional PON architectures are also not configured to sufficiently employ upcoming technologies such as next-generation PON (NG-PON, NG-PON2) based on time and wavelength division multiplexing (TWDM), which deploys at 40-Gb/s or more, or 100G-EPON, which are multi-wavelength PON systems.